The genes that make night owls

Late risers are genetically predisposed to needing a lie-in—and may be more likely to suffer mental health problems as a result. That’s the conclusion of a major new study that examined the genetics of some 700,000 people in the U.S. and U.K. By looking at how participants described themselves—a “morning person” or an “evening person”—researchers identified 351 genes associated with early rising. Previous research identified only 24 such genes. When researchers then looked for links to mental health issues, they found that night owls were about 10 percent more likely than early risers to develop schizophrenia, had a higher risk of depression, and reported being less happy on well-being questionnaires. Study leader Samuel Jones, from the U.K’s University of Exeter, says the 351 genes he and his team identified may affect how a person’s brain reacts to external light signals. “These small differences may have potentially significant effects on the ability of our body clocks to keep time effectively,” he tells The Guardian (U.K.). Jones says it remains unclear why night owls may be more susceptible to mental health issues, but suggests it could be because they have to work against their natural circadian rhythms in school and at work.